Electrical transmission or interconnection systems – Switching systems – Plural switches
Reexamination Certificate
1999-03-30
2001-01-30
Ballato, Josie (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
Plural switches
C307S141000
Reexamination Certificate
active
06181030
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains to computers and other information handling systems and, more particularly, to a power supply system for use with hot pluggable adapter cards in which a circuit averages the voltages at the power supply pins of the active I/O bus connectors to regulate the output voltage of the power supply, and in which the feedback voltage from the power supply pins of the I/O connectors to the input port of the power supply is switched ON or OFF at appropriate times.
FIG. 1
is a schematic diagram of a prior art computer system. Referring to this figure, power supply
101
is a well known power supply having a voltage output port Vout, a ground terminal GND, and two input ports Vsense+ and Vsense− for receiving a sense voltage that controls the voltage at the output port Vout. A resistor
102
and series connected FET switch
103
having a control input
103
a
are connected to the positive power supply pin
104
a
of a well known I/O bus connector
104
, to which a well known adapter card can be attached. In the typical prior art system, more than one I/O connector is usually included and connected to power supply
101
in a manner similar to that of connector
104
. The negative power supply pin
104
b
of connector
104
is connected to ground. The two terminals of the “current sensing” resistor
102
are connected to two Isense input terminals of a well known hot plug controller
105
. The voltage drop across resistor
102
is proportional to the power supply current flowing into the adapter card plugged into connector
104
and this voltage drop can be used by hot plug controller
105
to sense the presence of an adapter card in the “slot”, and to provide over current protection. The power supply voltage at pin
104
a
is connected to a Vsense input of hot plug controller
105
. A control output port of hot plug controller
105
is connected to the control input
103
a
of switch
103
and turns the switch OFF just before an adapter card is plugged into or removed from connector
104
, and turns the switch ON just after the adapter card is plugged into the slot.
While the prior art power supply system may work well when only one adapter card is connected to the I/O bus, unacceptable variations in the power supply voltage at the power supply pins of the various I/O connectors in the system can result, particularly if there is a significant difference in the power consumed by the various adapter cards. These unacceptable variations in power supply voltage can be deviations from the ideal or “spec” power supply voltage, as well as variations in the power supply voltage from one adapter card to the next. Accordingly, the invention described below regulates the power supply voltage such that the average voltage at the power supply pins of the active I/O connectors is within close tolerances of “spec”, and such that the deviation of the power supply voltage at any one I/O connector from spec is minimal.
SUMMARY OF THE INVENTION
Briefly, the invention is an information handling system including a bus having a first connector for the attachment of an adapter card, wherein the first connector includes a power supply voltage pin. A power supply has an output port and a sense voltage input port, wherein the voltage at the sense voltage input port controls the voltage at the output port of the power supply. A first switch is coupled between the output port of the power supply and the power supply voltage pin of the first connector. The first switch includes a control port. A first resistor is coupled between the output port of the power supply and the sense voltage input port, such that the first resistor provides sense voltage feedback to the sense voltage input port of the power supply. A second resistor has a first end coupled to the power supply pin of the first connector. A second switch is coupled between a second end of the second resistor and the sense voltage input port of the power supply. The second switch also includes a control port. The second resistor provides sense voltage feedback to the sense voltage input port of the power supply when the second switch is ON. Control circuitry includes a first output coupled to the control input of the first switch, and a second output coupled to the control input of the second switch. The control circuitry activates the first switch to provide power to the first connector subsequent to the attachment of an adapter card to the first connector, and the control circuitry deactivates the first switch to remove power from the first connector prior to the removal of an adapter card from the first connector. The control circuitry delays the activation of the second switch until after the first switch has been activated, and the control circuitry delays the deactivation of the first switch until after the second switch has been deactivated.
In another embodiment, the invention further includes a second connector for the attachment of another adapter card. The second connector also includes a power supply voltage pin. A third resistor has a first end coupled to the power supply pin of the second connector. A third switch is coupled between a second end of the third resistor and the sense voltage input port of the power supply. The third switch also includes a control port. The third resistor provides sense voltage feedback to the sense voltage input port of the power supply when the third switch is ON. When the second and third switches are ON, the sense voltage at the sense voltage input port of the power supply is a function of the average of the voltages at the power supply pins of the first and second connectors.
REFERENCES:
patent: 5894561 (1999-06-01), Kuan et al.
patent: 5910690 (1999-06-01), Dorsey et al.
Carpenter Brian Ashley
Ivins Thomas Dale
Ballato Josie
DeBeradinis Robert L.
International Business Machines - Corporation
McKinley Martin J.
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